Electronic sensing of an environment is useful in many contexts, including security, targeting adversaries, detecting things in the environment, providing imagery that depicts the environment, and the like. Electronic sensing may be particularly important when the information collected, such as electromagnetic radiation (EMR) in non-visible spectrums, cannot be seen by an unaided human eye. In some contexts, such as in an aircraft for example, it may also be desirable to collect information about the environment relatively rapidly, and in a continuous manner across a large field of regard, to ensure that the crew can be made aware of relevant events that may occur from any direction with respect to the aircraft, such as the approach of an enemy combatant, the launch of an anti-aircraft missile, the movements on the ground of combatants, and the like.
Information about the environment sensed in one waveband may provide information that is not ascertainable in other wavebands. For example, the signature of a missile plume may be particularly energetic in a particular infrared waveband, and less energetic in other infrared and visible wavebands. Thus, for early detection, it would be desirable to have a detector array limited to that particular infrared waveband. However, detectors are typically relatively broadband devices, capture EMR in a relatively wide range of wavebands, and, thus, lack the desired sensitivity in particular wavebands. The use of multiple detectors, each of which may be limited to a relatively narrow waveband, may not be practical in view of cost and size constraints. Generally, there are two types of detectors: scanning detectors and staring detectors, and each type offers advantages in different situations. A scanning detector is typically an array of pixels that has a relatively large number of rows with respect to the number of columns. The scanning detector is scanned across a scene in a direction perpendicular to the long dimension of the pixel array, and the trailing column of pixels may be continually read out at a rate based on the sweep rate of the detector. Because of the relatively small number of pixels read out at one time, the scanning detector may be scanned across the scene relatively quickly. The use of time delay and integration (TDI) processing in conjunction with a scanning detector results in relatively high sensitivity, but a scanning detector remains in motion continually, thus inhibiting the ability to collect additional information from an area deemed to be interesting during a single integration period. A staring detector is typically an array of pixels that has approximately an equal number of columns and rows. The staring detector generates a complete image of the portion of the scene within the field of view (FOV) of the staring detector at a given point in time, but read-out of the entire pixel array takes an amount of time that inhibits a high read-out framerate, and thus the staring detector is moved, if at all, at a relatively slow rate with respect to the scene. However, a staring detector allows for substantial integration times compared to a scanning detector, and thus allows more information to be derived from a scene.
Consequently, it may be desirable in many applications to have both a scanning detector and a staring detector. However, as mentioned above, the use of multiple detectors may not be practical in view of cost and size constraints of the particular application.